Use actual value of display scale factor from GetMonitorScaleFactor().

content/browser/web_contents/web_contents_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <utility>
@@ skipping 1003 matching lines @@
     const std::string& interface_name,
     WebContentsBindingSet* binding_set) {
   auto result =
       binding_sets_.insert(std::make_pair(interface_name, binding_set));
   DCHECK(result.second);
   return base::Bind(&WebContentsImpl::RemoveBindingSet,
                     weak_factory_.GetWeakPtr(), interface_name);
 }
 
 void WebContentsImpl::UpdateDeviceScaleFactor(double device_scale_factor) {
+  LOG(ERROR) << "WebContentsImpl::UpdateDeviceScaleFactor("
+             << device_scale_factor << ")";
   SendPageMessage(
       new PageMsg_SetDeviceScaleFactor(MSG_ROUTING_NONE, device_scale_factor));
 }
 
 void WebContentsImpl::GetScreenInfo(ScreenInfo* screen_info) {
   if (GetView())
     GetView()->GetScreenInfo(screen_info);
 }
 
 std::unique_ptr<WebUI> WebContentsImpl::CreateSubframeWebUI(
@@ skipping 4180 matching lines @@
   dialog_manager_ = dialog_manager;
 }
 
 void WebContentsImpl::RemoveBindingSet(const std::string& interface_name) {
   auto it = binding_sets_.find(interface_name);
   if (it != binding_sets_.end())
     binding_sets_.erase(it);
 }
 
 }  // namespace content